The present invention relates to the reduction of liquid retention zones in circuits for transporting liquids such as food liquids. The subject of the invention is more particularly a device for the sealed connection of a duct, having no retention zone into which the liquid could pass and stagnate. Such zones are particularly problematic when the fluid in question is a food liquid or other liquid that is liable to deteriorate under the action of microorganisms since the retention zones are difficult to clean and so the liquid risks remaining trapped there and deteriorating, contaminating the liquid subsequently transported through the circuit. The same problem of contamination arises when a change of liquid is necessary, for example in the case of a change of shade in a paint circuit.
Conventionally found in a device for the sealed connection of a duct is a tubular body that delimits a channel of which an end section is designed to accommodate an end portion of the duct and is provided with an axial stop that limits the insertion of the duct into the tubular body. The end section of the tubular body also receives a toothed washer or a catching gripper of the duct so as to retain the duct in the tubular body. Finally a seal provides a sealed connection of the duct in the tubular body of the connection device.
In a first embodiment, the seal extends into the tubular body in order to grip the duct to be connected. Sealing is thus produced at the external surface of the duct. The quality of sealing is thus dependent on the state of the external surface of the duct which is subjected, before the connection, to external harm such as impacts and friction which is liable to produce scratches and other types of damage. Moreover, this type of mounting brings about retention zones by allowing the liquid to pass between the stop and the annular front face of the duct.
In a second embodiment, the seal adjoins the stop in order to be compressed between the stop and the annular front face of the duct. This limits the retention zones. However, the quality of sealing is dependent on the state of the annular front face of the duct which is generally obtained by means of cutting carried out on site by an operator. This results in scratches on this face, which is otherwise only rarely perfectly perpendicular to the axis of the duct.
According to a third embodiment, the body comprises an internal tubular appendix which is coaxial with the end section of the tubular body and which fits into the interior of the duct during the insertion of the latter into the tubular body. Sealing is thus provided by an O-ring seal disposed in an outer groove provided on the appendix so as to come into contact with the internal surface of the duct, the surface state of which is generally good. This seal is disposed at a distance from the free end of the appendix, creating a retention zone. The connectors having an internal appendix also reduce the flow cross section of the fluid and make an expensive increase in the cross section of the ducts necessary.
It is an aim of the invention to reduce the penetration of liquid circulating in a duct into retention zones.